Advertisements
Advertisements
प्रश्न
State whether the following statement is true or false. Correct the false statement.
Phenolphthalein is a natural indicator.
विकल्प
True
False
Advertisements
उत्तर
This statement is False.
Explanation:
Phenolphthalein is a synthetic indicator.
APPEARS IN
संबंधित प्रश्न
A milkman adds a very small amount of baking soda to fresh milk. Why does he shift the pH of the fresh milk from 6 to slightly alkaline?
Why should curd and other sour foodstuffs (like lemon juice, etc.) not be kept in metal containers (such as copper and brass vessels)?
Two solutions X and Y have pH = 4 and pH = 8, respectively. Which solution will give alkaline reaction and which one acidic?
The pH values of three acids A, B and C having equal molar concentrations are 5.0, 2.8 and 3.5 respectively. Arrange these acids in order of the increasing acid strengths.
Someone put some universal indicator paper into vinegar. The pH is 3. What does this tell you about the vinegar?
The pH values of five solutions A, B, C, D and E are given below:
| A | 1 |
| B | 5 |
| C | 7 |
| D | 11 |
| E | 13 |
Which solution is
- weakly alkaline
- neutral
- strongly acidic
- strongly alkaline, and
- weakly acidic?
Here are some results of solutions tested with universal indicator paper:
| Sulphuric acid | : | Red |
| Metal polish | : | Dark blue |
| Washing-up liquid | : | Yellow |
| Milk of magnesia | : | Light blue |
| Oven cleaner | : | Purple |
| Car battery acid | : | Pink |
Arrange the solutions in order of their increasing pH values (starting with the one with the lowest pH).
Which of the following is not a natural indicator?
Take a small beetroot vegetable and cut it into pieces. Boil them in hot water and filter the extract. Take two test tubes. Take sodium hydroxide solution in one test tube and vinegar or lemon juice in another test tube. Add beetroot extract slowly. Observe the colour change. What do you infer?
Using the knowledge of acids and bases, write a secret message with the help of baking soda and beet root. Explain how it works.
(Hint: Prepare baking soda solution in water. Use this solution to write the message on a sheet of white paper with a cotton bud. Rub a slice of fresh beetroot over the message.)
